JP2017198100A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize both Otto cycle and a miller cycle at an internal combustion engine while an opening or closing structure for an intake valve is made as simple as possible.SOLUTION: This invention relates to an internal combustion engine operated in such a way that when a lock part 60 is set to a non-lock position, an engaging part 50 arranged at a cam shaft 20 is pushed against an advanced side end part 31A of an idling allowable part 31 at an intake cam 30 by a driving rotational force of a cam shaft 20 until an intake cam 30 fully opens an intake valve, and upon full open of the intake valve by the intake cam 30, the advanced side end part 31A of the idling allowable part 31 at the intake cam 30 is moved away from the engaging part 50 arranged at the cam shaft 20 by a spring force of the intake valve, and the intake cam 30 is moved in idling state only by an idling angle in a cam shaft rotating direction in respect to the cam shaft 20 until a counter-advancing end part 31B of the idling allowable part 31 is pushed against the engaging part 50 arranged at the cam shaft 20.SELECTED DRAWING: Figure 11

Description

  The present invention relates to an internal combustion engine.

  In the internal combustion engine, a mirror cycle is known in which the stroke length of the compression stroke is effectively made shorter than the stroke length of the expansion stroke by closing the intake valve at a timing later than the intake bottom dead center in the intake stroke of the cylinder. Yes.

  The Miller cycle, which has a larger actual expansion ratio than the actual compression ratio, can reduce the amount of exhaust heat and increase the thermal efficiency while reducing the pumping loss, compared to the Otto cycle in which the actual compression ratio and the actual expansion ratio are substantially equal. This is advantageous.

  Conventionally, as a technique for mirror cycle of an internal combustion engine, there is one using a variable valve timing mechanism as described in Patent Document 1. This variable valve timing mechanism has two different intake cams with different cam profiles and different intake valve closing timings, and either one of these two intake cams is controlled by a hydraulic piston mechanism or the like. It is linked to the rocker arm of the intake valve. According to the intake cam having the cam profile suitable for the mirror cycle, the mirror cycle can be realized. With an intake cam with a cam profile suitable for the Otto Circle, an Otto cycle can be realized.

JP 2004-183510 A

  In the internal combustion engine described in Patent Document 1, it is necessary to prepare two types of intake cams having different cam profiles as intake valve opening / closing structures in order to realize both the Otto cycle and the mirror cycle, which is complicated.

  An object of the present invention is to realize an Otto cycle and a mirror cycle in an internal combustion engine while simplifying the opening / closing structure of an intake valve as much as possible.

  In an internal combustion engine in which an intake valve is driven against a spring force by an intake cam pivotally supported by a camshaft, and the intake port is opened and closed by the intake valve, the intake cam is relative to the camshaft. The engaging portion provided on the camshaft is pivotally supported, and the advancing end on one end and the non-advancing end on the other end along the camshaft rotation direction of the air movement allowance provided on the intake cam. The camshaft and the intake air can be moved in a range that can be moved between the camshaft and the camshaft, and the engagement portion provided on the camshaft is engaged with the advancing end of the airflow allowance portion provided on the intake cam. There is a lock part that can be switched between a lock position that fixes the cam so that it cannot rotate relative to a non-lock position that is not fixed, and when the lock part is set to the non-lock position, the intake cam controls the intake valve. Until fully opened, the engaging part provided on the camshaft by the driving rotational force of the camshaft After the intake cam is pressed against the advancing end of the intake cam and the intake cam fully opens the intake valve, the advancing end of the aerodynamic allowance of the intake cam is used as a camshaft by the spring force of the intake valve. The intake cam is moved in the camshaft rotation direction with respect to the camshaft until it is separated from the provided engaging portion and the end of the counterclockwise side of the idling allowable portion is pressed against the engaging portion provided on the camshaft. Until the intake cam is fully idled and the intake cam fully closes the intake valve, the spring force of the intake valve causes the counter-traveling side end of the intake cam to be pushed against the engaging portion provided on the camshaft. After the intake cam fully closes the intake valve, the engagement portion provided on the camshaft is separated from the counter-advance end of the airflow allowance portion of the intake cam by the driving rotational force of the camshaft, and the airflow allowance portion The camshaft against the intake cam until it is pressed against the leading end of the camshaft. The intake cam is fixed to the camshaft so as not to rotate relative to the camshaft when the lock portion is set at the lock position.

  According to a second aspect of the invention, in the first aspect of the invention, the operating angle θ1 at which the intake cam drives the intake valve when the lock portion is set to the non-lock position is such that the lock portion is at the lock position. When set, the intake cam is smaller than the operating angle θ2 for driving the intake valve by the idle angle α of the engaging portion provided on the camshaft.

  According to a third aspect of the invention, in the invention according to the first or second aspect, the lock portion is provided on the cam shaft, and the lock portion set at the lock position is opposite to the air movement allowance portion provided on the intake cam. When the advancing side end can be engaged and the lock portion is set to the locked position, the engaging portion provided on the cam shaft engages with the advancing side end of the idling allowable portion of the intake cam, and the cam A lock portion provided on the shaft is engaged with a counter-advance side end portion of the idling allowable portion in the intake cam, and the intake cam is fixed to the cam shaft so as not to be relatively rotatable.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the lock portion is inserted into a hollow portion provided in the cam shaft so as to be movable in the axial direction of the cam shaft, and is along the axial direction. A spool that can be switched between a non-locking position and a locking position, and a concave portion and a convex portion that are loaded in a roll loading portion provided on the outer peripheral wall surrounding the hollow portion of the camshaft and are arranged in parallel in the axial direction of the spool And a lock ball that immerses or projects into and out of the outer peripheral wall of the camshaft, and an actuator that switches the spool between the unlocked position and the locked position, and the actuator moves the spool to the unlocked position. When set, the lock ball is inserted into the outer peripheral wall of the camshaft and disengaged from the counter-advance side end of the air movement allowable portion of the intake cam. When the spool is set at the lock position, the lockball is moved to the camshaft. Outside Protrudes from the wall is obtained so as to be engaged with the counter-leading side end portion of the lost motion allowing portion in the intake cam.

(Claims 1 and 2)
(a) When the locking part is set to the unlocked position, the engaging part provided on the camshaft pushes the intake cam and the intake cam opens the intake valve in the process of opening the intake valve. After the valve is fully opened, the intake cam is idled by the idle angle α in the camshaft rotation direction. As a result, the operating angle θ1 of the intake cam becomes smaller by the above-mentioned idle angle α than when the intake cam does not idle (mirror cycle), and the intake valve closes at an early timing, and the Otto cycle Is realized.

  When the lock part is set to the lock position and the intake cam does not idle, the intake cam operating angle θ2 increases by the above-mentioned idle angle α, and the intake valve closes at a later timing, and the mirror cycle is Realize.

(Claim 3)
(b) The lock portion is provided on the cam shaft, and the lock portion set at the lock position can be engaged with the counter-advance side end portion of the idling allowable portion provided on the intake cam. As a result, when the lock portion is set at the lock position, the engaging portion provided on the cam shaft engages with the advancing side end portion of the idle motion allowing portion in the intake cam, and the lock portion provided on the cam shaft The intake cam is fixed to the camshaft so as to be relatively non-rotatable with certainty and simpleness by engaging with the counter-advance end of the idling portion of the cam.

(Claim 4)
(c) By operating the actuator to switch the spool to the locked position or the unlocked position, the lock ball that engages with the concave or convex portion of this spool is moved to the opposite end of the idling allowable portion of the intake cam. It can be easily disengaged or engaged with the part.

FIG. 1 is a schematic diagram showing a valve opening / closing state in the Otto cycle mode. FIG. 2 is a schematic view showing a valve opening / closing state in the Otto cycle mode. FIG. 3 is a schematic diagram showing a valve opening / closing state in the Otto cycle mode. FIG. 4 is a schematic diagram showing a valve open / close state in the Otto cycle mode. FIG. 5 is a schematic diagram showing a valve opening / closing state in the Otto cycle mode. FIG. 6 is a schematic diagram showing a valve opening / closing state in the mirror cycle mode. FIG. 7 is a schematic diagram showing a valve opening / closing state in the mirror cycle mode. FIG. 8 is a schematic view showing a valve opening / closing state in the mirror cycle mode. FIG. 9 is a schematic view showing a valve opening / closing state in the mirror cycle mode. FIG. 10 is a schematic diagram showing a valve opening / closing state in the mirror cycle mode. FIG. 11 shows an Otto cycle mode, where (A) is a cross-sectional view showing a state before the valve is fully opened, and (B) is a cross-sectional view showing a state after the valve is fully opened. 12A and 12B show the mirror cycle mode, where FIG. 12A is a cross-sectional view, and FIG. 12B is a cross-sectional view taken along line BB in FIG. 13A and 13B show a working angle of the intake cam, FIG. 13A is a schematic diagram showing a working angle in the Otto cycle mode, and FIG. 13B is a schematic diagram showing a working angle in the mirror cycle mode. FIG. 14 is a valve timing diagram of the exhaust valve and the intake valve.

  FIG. 1 shows a main part of an internal combustion engine 10 used in a vehicle or the like of the present embodiment, and can be operated by switching between an Otto cycle mode and a mirror cycle mode using natural gas, light oil, gasoline or the like as fuel.

  The cylinder head 11 of the internal combustion engine 10 is provided with an ignition plug (not shown) and a fuel injection valve (not shown) for each cylinder, an intake port 12 through which intake air flows into the cylinder, and the cylinder And an exhaust port (not shown) through which exhaust flows out. The intake port 12 is provided with an intake valve 13 for opening and closing the intake port 12, and the exhaust port is provided with an exhaust valve (not shown) for opening and closing it.

Hereinafter, the opening / closing structure of the intake valve 13 will be described in detail.
The internal combustion engine 10 of the present embodiment has a cam shaft 20 to which a driving rotational force brought from a crankshaft is transmitted, and resists the spring force of the valve spring 40 by an intake cam 30 pivotally supported by the camshaft 20. Then, the intake valve 13 is driven, and the intake port 12 is opened and closed by the intake valve 13. The intake valve 13 is attached in the direction in which the intake port 12 is closed by the spring force of the valve spring 40 interposed between the valve spring retainer 41 attached to the valve stem 13A and the upper surface of the cylinder head 11. It is energized.

  Here, as shown in FIG. 11, the intake cam 30 is pivotally supported so as to be relatively rotatable with the cam shaft 20, and an engagement portion 50 provided on the cam shaft 20 is an air motion allowance portion 31 provided on the intake cam 30. Is made to be able to move in an idling range R sandwiched between one advancing end 31A along the camshaft rotation direction N and the other advancing end 31B.

  The cam shaft 20 has a hollow shape, and is provided in a single circumferential position in a cross section perpendicular to the axis of the cylindrical outer peripheral wall 21 that surrounds the hollow portion H, and expands outward in the radial direction. The groove 22 extends in the axial direction, and a part of the arc-shaped cross section (substantially half cross-section) of the round bar-shaped engagement portion 50 is fitted into the semi-arc-shaped groove 22. The remaining portion of the camshaft 20 protrudes outward from the cylindrical outer peripheral wall 21 of the camshaft 20.

  In addition, the intake cam 30 includes an idling allowance portion 31 provided on the inner peripheral surface of the cam shaft 20 that is fitted to the cylindrical outer peripheral wall 21 so as to be relatively rotatable. The idling allowable portion 31 faces the outer peripheral surface of the cylindrical outer peripheral wall 21 of the camshaft 20 and extends over the above-described idly movable range R along the circumferential direction of the outer peripheral surface. A groove surface between the advancing side end portion 31A and the counter-advancing side end portion 31B in the idling allowable portion 31 is slid by an engaging portion 50 projecting from the cylindrical outer peripheral wall 21 of the camshaft 20 through a minute gap. The groove surface at the advancing side end portion 31A and the advancing side end portion 31B is engaged with the engaging portion 50 protruding from the cylindrical outer peripheral wall 21 of the camshaft 20 in pressure contact. Make an arc shape to get.

  Further, in the internal combustion engine 10, the camshaft 20 and the intake cam 30 are in a state where the engaging portion 50 provided on the camshaft 20 is engaged with the advancing side end portion 31 </ b> A of the idling allowable portion 31 provided on the intake cam 30. And a lock portion 60 that can be switched and set between a lock position (FIG. 12A) for fixing the two to be non-rotatable and a non-lock position that is not fixed (FIG. 11A).

  In the present embodiment, the lock unit 60 includes a spool 61, a lock ball 62, and an actuator 63, as shown in FIG. The spool 61 is inserted into a hollow portion H provided in the cam shaft 20 so as to be movable in the axial direction of the cam shaft 20, and an unlocked position (FIG. 11) and a locked position (FIG. 12) along the axial direction. Can be switched to The lock ball 62 is loaded into a ball loading portion 23 provided on the cylindrical outer peripheral wall 21 surrounding the hollow portion H of the camshaft 20, and alternately turns into the concave portions 61 </ b> A and the convex portions 61 </ b> B arranged in parallel in the axial direction of the spool 61. Engage and immerse (FIG. 11) or protrude (FIG. 12) into and out of the cylindrical outer peripheral wall 21 of the camshaft 20. In the present embodiment, hole-shaped ball loading portions 23 are loaded at three positions along the axial direction of the cylindrical outer peripheral wall 21 of the camshaft 20, and a plurality (three in this embodiment) of the lock balls 62 are loaded. Each is loaded in the ball loading section 23. Correspondingly, the spool 61 is provided with three sets of the annular concave portion 61A and the annular convex portion 61B arranged in the axial direction in the axial direction. The actuator 63 reciprocates the spool 61 in the axial direction by electric power (electric force or the like) or fluid pressure (hydraulic pressure or the like), and switches the spool 61 between the unlocked position and the locked position. Therefore, when the actuator 63 sets the spool 61 to the unlocked position (FIG. 11), the lock portion 60 is inserted into the cylindrical outer peripheral wall 21 of the camshaft 20 and the air movement allowance portion 31 in the intake cam 30 is set. The non-engagement with the counter-advancing side end 31B. On the other hand, when the actuator 63 sets the spool 61 in the locked position (FIG. 12), the lock ball 62 protrudes from the cylindrical outer peripheral wall 21 of the cam shaft 20 and the end of the idling allowable portion 31 in the intake cam 30 on the counter-advance side. Engage with the part 31B.

However, (A) in the internal combustion engine 10, when the lock portion 60 (lock ball 62) is set to the unlocked position by the actuator 63 (Otto cycle mode) (FIG. 11),
i. Until the intake cam 30 fully opens the intake valve 13 (the intake cam 30 is in pressure contact with the valve stem 13A in the rotational direction N, the upwardly inclined surface extending from the base circle of the profile to the top), and the camshaft 20 is driven to rotate. Thus, the engaging portion 50 provided on the camshaft 20 is pressed against the advancing side end portion 31A of the idling allowable portion 31 in the intake cam 30.
ii. After the intake cam 30 fully opens the intake valve 13 (the intake cam 30 presses against the valve stem 13A on the descending slope surface from the top of the profile to the base circle in the rotational direction N), the valve spring in the intake valve 13 40, the advancing side end 31A of the idling allowable portion 31 in the intake cam 30 is separated from the engaging portion 50 provided on the cam shaft 20, and the counter-advancing end 31B of the idling allowable portion 31 is camped. The intake cam 30 is caused to idle by the aerodynamic angle α in the cam shaft rotation direction N with respect to the cam shaft 20 until it is pressed against the engaging portion 50 provided on the shaft 20.
iii. Until the intake cam 30 fully closes the intake valve 13 (the intake cam 30 presses the basic circle of the profile against the valve stem 13A in the rotational direction N), the intake cam 30 is caused by the spring force of the valve spring 40 in the intake valve 13. The counter-traveling side end portion 31B of the idling allowable portion 31 is pressed against the engaging portion 50 provided on the camshaft 20,
iv. After the intake cam 30 fully closes the intake valve 13 (the intake cam 30 presses the basic circle of the profile against the valve stem 13A in the rotation direction N), the camshaft 20 is driven by the driving rotational force of the camshaft 20. The camshaft 20 is moved to the intake cam 30 until the engaging portion 50 provided on the intake cam 30 is separated from the non-advance end 31B of the air movement allowance 31 in the intake cam 30 and pressed against the advance end 31A of the air movement allowance 31. 30 is moved in the camshaft rotation direction N by an aerodynamic angle α.

  In the above iv, the engaging portion 50 provided on the camshaft 20 is separated from the non-advancing side end portion 31B of the idling allowable portion 31 in the intake cam 30, and pushed to the advancing end portion 31A of the idling allowable portion 31. As a force acting on the intake cam 30 to be attached, in addition to the driving rotational force of the camshaft 20, the spring force of a return spring comprising a torsion coil spring or the like interposed between the camshaft 20 and the intake cam 30 May be used. The spring force of the return spring rotates the intake cam 30 in the direction opposite to the cam shaft rotation direction N with respect to the cam shaft 20.

  On the other hand, (B) when the lock portion 60 (lock ball 62) is set to the lock position by the actuator 63 (mirror cycle mode) (FIG. 12), the engagement portion 50 provided on the cam shaft 20 is empty in the intake cam 30. The lock portion 60 (lock ball 62) provided on the cam shaft 20 is engaged with the counter-advance side end portion 31B of the idle movement allowance portion 31 in the intake cam 30 while engaging with the advance side end portion 31A of the movement allowance portion 31. The intake cam 30 is fixed to the camshaft 20 so as not to be relatively rotatable.

  FIG. 13 shows the operating angle θ1 (FIG. 13 (A)) at which the intake cam 30 drives the intake valve 13 when the lock portion 60 (lock ball 62) is set to the unlocked position (Otto cycle mode). When the portion 60 (the lock ball 62) is set to the locked position (mirror cycle mode), the working angle θ2 (FIG. 13B) at which the intake cam 30 drives the intake valve 13 is compared. is there. In the profile (solid line) of the intake cam 30 that is not idling, a indicates a boundary point between the basic circle and the upward gradient surface, b indicates a top portion, and c indicates a boundary point between the basic circle and the downward gradient surface. In the profile (two-dot chain line) of the intake cam 30 after being idled by the spring force F of the valve spring 40, b 'represents the top portion, and c' represents the boundary point between the basic circle and the downward slope surface. o indicates the center point of the intake cam 30. As apparent from FIG. 13, the operating angle θ1 (∠aoc ′) at which the intake cam 30 drives the intake valve 13 when the lock portion 60 (lock ball 62) is set to the non-lock position is the lock portion 60 (lock As shown in FIG. 13, the above-described engagement portion 50 provided on the camshaft 20 is larger than the operating angle θ2 (∠aoc) at which the intake cam 30 drives the intake valve 13 when the ball 62) is set at the locked position. Is smaller by the aerodynamic angle α.

  Therefore, as shown in FIG. 14, the valve timing of the intake valve 13 is the closing timing of the valve timing A (Otto cycle mode) in which the lock portion 60 is set to the unlocked position, and the lock portion 60 is set to the lock position. The valve timing B (mirror cycle mode) is made earlier than the closing timing of the above-described idle angle α. In other words, the valve closing timing of the valve timing B in the mirror cycle mode is later than the valve closing timing by the valve timing A of the Otto cycle mode by the above-mentioned idle movement angle α.

  Therefore, the ECU (control means) 70 of the internal combustion engine 10 needs to be Otto cycle based on the detection result of the engine speed sensor, the accelerator position sensor, the vehicle speed sensor, etc., for example, because the engine operating state is in a low rotation range. When it is determined, the ECU 70 controls the actuator 63 so as to set the lock portion 60 (lock ball 62) to the unlocked position, and sets the valve timing of the intake valve 13 to the Otto cycle mode. On the other hand, for example, when it is determined that the mirror cycle is necessary because the engine operating state is in the middle / high rotation range, the ECU 70 controls the actuator 63 so as to set the lock portion 60 (lock ball 62) to the lock position, The valve timing of the intake valve 13 is set to the mirror cycle mode.

Hereinafter, the Otto cycle mode and the mirror cycle mode will be described in detail.
(A) Otto cycle mode (Figs. 1 to 5)
The lock part 60 (lock ball 62) is set to the unlocked position by the actuator 63 (FIG. 11).

  (1) Until the intake cam 30 fully opens the intake valve 13 from the fully closed state, as shown in FIGS. 1 and 2, the cam shaft 20 that receives the driving rotational force is the engaging portion 50 provided on the cam shaft 20. The intake cam 30 is rotated while pressing it against the advancing side end 31A of the idling allowance portion 31 of the intake cam 30, and the upward gradient surface from the basic circle to the top of the profile of the intake cam 30 is the spring force of the valve spring 40. The valve stem 13A is pushed down against this, and the intake valve 13 is opened.

  (2) After the intake cam 30 has fully opened the intake valve 13, the valve stem 13 A that receives the spring force of the valve spring 40 starts from the top of the profile of the intake cam 30 as shown in FIGS. 3 and 4. Is in pressure contact with the descending slope surface in the camshaft rotation direction N, and the advancing side end portion 31A of the air movement allowance portion 31 of the intake camshaft 30 is separated from the engagement portion 50 provided on the camshaft 20, thereby causing the air motion allowance portion. The intake cam 30 is caused to idle with respect to the camshaft 20 in the camshaft rotation direction N by an aerodynamic angle α until the counter-advancing side end portion 31B of 31 is pressed against the engaging portion 50 provided on the camshaft 20.

  (3) After the intake cam 30 is idled, until the intake cam 30 fully closes the intake valve 13, the valve stem 13A that receives the spring force of the valve spring 40 cams the down-gradient surface of the profile of the intake cam 30 In a state where pressure is applied in the shaft rotation direction N, the counter-advance side end portion 31 </ b> B of the idle motion allowing portion 31 in the intake camshaft 30 is pressed against the engaging portion 50 provided on the camshaft 20. The intake cam 30 rotates together with the camshaft 20 so as to be driven by the camshaft 20 while pressing the counter-advance side end portion 31B of the idling allowance portion 31 against the engaging portion 50 provided on the camshaft 20, and the intake valve 13 Close.

  (4) After the intake cam 30 fully closes the intake valve 13, the camshaft 20 that receives the driving rotational force causes the engaging portion 50 provided on the camshaft 20 to move to the air movement allowance portion 31 of the intake cam 30. The camshaft 20 is moved idly in the camshaft rotation direction N in the camshaft rotation direction N until the camshaft 20 is separated from the counter-advancing side end portion 31B and pressed against the advancing side end portion 31A of the idling allowance portion 31. Let Thus, the process returns to the initial stage where the intake valve 13 starts to be opened in the above (1).

(B) Mirror cycle mode (Figs. 6 to 10)
The lock portion 60 (lock ball 62) is set to the lock position by the actuator 63, and the intake cam 30 is fixed to the cam shaft 20 so as not to be relatively rotatable (FIG. 12).

  (1) Until the intake cam 30 fully opens the intake valve 13 from the fully closed state, as shown in FIGS. 6 and 7, the camshaft 20 receiving the driving rotational force rotates the intake cam 30, and the intake cam 30 The ascending slope from the basic circle of the profile to the top pushes down the valve stem 13A against the spring force of the valve spring 40 and opens the intake valve 13.

  (2) From the time when the intake cam 30 is fully opened until the intake valve 13 is fully closed, the valve stem 13A receiving the spring force of the valve spring 40 is the profile of the intake cam 30, as shown in FIGS. The intake camshaft 30 rotates together with the camshaft 20 so as to be driven by the camshaft 20 and closes the intake valve 13 under a state in which the descending slope surface extending from the top of the base to the base circle is pressurized in the camshaft rotation direction N.

  (3) After the intake cam 30 fully closes the intake valve 13, the camshaft 20 that has received the driving rotational force rotates the intake cam 30, and returns to the initial stage where the intake valve 13 starts to open in the above-described (1). .

According to this embodiment, there exist the following effects.
(a) When the lock portion 60 is set to the unlocked position, the engaging portion 50 provided on the camshaft 20 pushes the intake cam 30, and the intake cam 30 opens the intake valve 13. Thus, after the intake cam 30 fully opens the intake valve 13, the intake cam 30 is idled by the aerodynamic angle α in the camshaft rotation direction. As a result, the operating angle θ1 of the intake cam 30 becomes smaller by the above-mentioned idle angle α than when the intake cam 30 does not idle (mirror cycle), and the intake valve 13 closes at an early timing. Realize the Otto cycle.

  When the lock portion 60 is set to the lock position and the intake cam 30 does not idle, the operating angle θ2 of the intake cam 30 increases by the above-described idle angle α, and the intake valve 13 closes at a late timing. Realize the mirror cycle.

  (b) The lock portion 60 is provided on the camshaft 20, and the lock portion 60 set at the lock position can be engaged with the counter-advance side end portion 31 </ b> B of the idling allowable portion 31 provided on the intake cam 30. . Thereby, when the lock part 60 is set to the lock position, the engaging part 50 provided on the camshaft 20 engages with the advancing side end part 31A of the idling allowable part 31 in the intake cam 30, and the camshaft 20 The lock portion 60 provided on the intake cam 30 engages with the counter-advance side end portion 31B of the air movement allowance portion 31 of the intake cam 30, and the intake cam 30 is fixed to the camshaft 20 securely and simply so as not to be relatively rotatable.

  (c) When the spool 61 is switched to the locked position or the unlocked position by the actuator 63, the lock ball 62 that is engaged with the concave portion 61A or the convex portion 61B of the spool 61 It is possible to easily disengage or engage with the counter-advance side end portion 31B of the allowance portion 31.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, in the present invention, the lock portion rotates the cam shaft and the intake cam relative to each other in a state where the engaging portion provided on the cam shaft engages with the advancing side end portion of the air movement allowance portion provided on the intake cam. It is only necessary to be able to switch between a locking position where it is impossible to fix and a non-locking position where it is not fixed. It does not need to be.

  In the present invention, the intake cam is not limited to directly driving the valve stem of the intake valve, but may be one that drives the valve stem of the intake valve via a rocker arm or the like.

  According to the present invention, in an internal combustion engine, an Otto cycle and a mirror cycle can be realized while simplifying an intake valve opening / closing structure as much as possible.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Intake port 13 Intake valve 20 Cam shaft 21 Outer peripheral wall 23 Ball | bowl loading part 30 Intake cam 31 Pneumatic motion permissible part 31A Advancing side end 31B Non-advancing end 40 61A Concave portion 61B Convex portion 62 Lock ball 63 Actuator

Claims (4)

In an internal combustion engine in which an intake valve is driven against a spring force by an intake cam pivotally supported by a camshaft, and the intake port is opened and closed by the intake valve.
The intake cam is pivotally supported by the camshaft so that the camshaft is relatively rotatable, and the engaging portion provided on the camshaft is an advance side end portion and the other end on one end side along the camshaft rotation direction of the idling allowable portion provided on the intake cam. It is made possible to move in the range that can be sandwiched between the side of the counter-advancing side,
The locking position for fixing the camshaft and the intake cam so as not to rotate relative to each other is not fixed while the engaging portion provided on the camshaft is engaged with the advancing side end of the idling allowable portion provided on the intake cam. It has a lock part that can be switched to the non-lock position,
When the lock portion is set to the non-lock position, the engaging portion provided on the camshaft is driven by the driving rotational force of the camshaft until the intake cam fully opens the intake valve. After the intake cam is fully opened by the intake cam, the advancing end of the idle movement allowable portion of the intake cam is separated from the engagement portion provided on the cam shaft by the intake valve spring force, The intake cam is caused to idle with respect to the camshaft in the camshaft rotation direction by an aerodynamic angle α until the opposite end of the allowance portion is pressed against the engaging portion provided on the camshaft, and the intake cam Until the valve is fully closed, the counter-advance side end portion of the air movement allowable portion of the intake cam is pressed against the engaging portion provided on the camshaft by the spring force of the intake valve, and the intake cam fully closes the intake valve. Is an engaging portion provided on the camshaft by the driving rotational force of the camshaft. The camshaft is moved away from the non-advanced end of the air movement allowance portion of the intake cam and the camshaft is moved in the camshaft rotation direction relative to the intake cam by an air movement angle α until it is pressed against the advancement end of the airflow allowance portion. Configured to run idle,
An internal combustion engine, wherein the intake cam is fixed to the camshaft so as not to rotate relative to the camshaft when the lock portion is set at the lock position.   The operating angle θ1 at which the intake cam drives the intake valve when the lock portion is set to the unlocked position is greater than the operating angle θ2 at which the intake cam drives the intake valve when the lock portion is set to the locked position. The internal combustion engine according to claim 1, which is smaller by an aerodynamic angle α of an engaging portion provided on the camshaft. The lock portion is provided on the camshaft, and the lock portion set at the lock position is engageable with the counter-advance side end portion of the idling allowable portion provided on the intake cam.
When the lock portion is set to the lock position, the engaging portion provided on the cam shaft engages with the advancing side end portion of the idling allowable portion in the intake cam, and the lock portion provided on the cam shaft is empty in the intake cam. The internal combustion engine according to claim 1 or 2, wherein the intake cam is fixed to the camshaft so as not to rotate relative to the camshaft. The lock part is
A spool that is inserted into a hollow portion provided in the cam shaft and is movable in the axial direction of the cam shaft, and is switchable between an unlocked position and a locked position along the axial direction;
It is loaded into a roll loading section provided on the outer peripheral wall surrounding the hollow portion of the cam shaft, and is alternately engaged with the concave portion and the convex portion arranged in parallel in the axial direction of the spool so as to be immersed in or out of the outer peripheral wall of the cam shaft. A protruding lock ball,
An actuator for switching the spool between an unlocked position and a locked position;
When the actuator sets the spool to the unlocked position, the lock ball is inserted into the outer peripheral wall of the camshaft and disengaged from the end of the intake cam on the counter-advancing side, and the spool is set to the locked position. The internal combustion engine according to claim 3, wherein the lock ball protrudes from the outer peripheral wall of the cam shaft and is engaged with the counter-advance side end portion of the idle motion allowing portion in the intake cam.

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